Research Finds Major Movement Detected Along San Andreas Fault

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Once thought to be immune from major quakes, the so-called creeping segment of the San Andreas Fault can potentially set off a temblor affecting both the northern and southern portions of the state.

A new analysis of GPS data has revealed previously undiscovered movement along the San Andreas Fault, which forms the tectonic boundary between the Pacific Plate and the North American plate and spans much of California.

According to the analysis, which is built on records that have been available for over a decade, large sections of land on either side of the fault are moving up or down every year in what, seismically speaking, could be considered "major movement."

"While the San Andreas GPS data has been publicly available for more than a decade, the vertical component of the measurements had largely been ignored in tectonic investigations because of difficulties in interpreting the noisy data,” said Samuel Howell, the lead author of the study. “Using this technique, we were able to break down the noisy signals to isolate a simple vertical motion pattern that curiously straddled the San Andreas fault.”

The GPS records, which were studied by a slew of research teams from University of Hawaii at Manoa, University of Washington and the Scripps Institution of Oceanography, also reveal nearly 125-mile long "lobes" of motion that straddles the fault system. Although the motion has been predicted before, it had never been documented.

To anyone who isn't studying fault lines, the data may not mean much at this point. But many researchers have said that this new insight into how the fault operates could help them predict "The Big One" -- the large earthquake that many believe is overdue to hit California.